Pathogenesis Of Colitis-associated Cancer Research Articles

Immunopathogenesis of Colitis-Associated Cancer in an Animal Model

Chronic inflammation, such as that seen in patients with inflammatory bowel disease (IBD), greatly increases the risk of developing colon cancer. Growing evidence supports a role for T cell-mediated immune response and release of various cytokines in the pathogenesis of colitis-associated cancer (CAC). In fact, CD4+ effector T cells promote chronic inflammation associated with IBD through release of proinflammatory cytokines, which leads to initiation and progression of colon cancer. Furthermore, CD8+ T cells reduce tumor growth through cancer immunosurveillance, which can also contribute to intestinal inflammation and thereby might promote tumor growth. In contrast, regulatory T cells (Tregs) release the immunosuppressive cytokines IL-10, TGF-β and thus have protective effects in CAC. In addition, dendritic cells (DCs) are important components of antitumor immunity. Recently, a novel mouse model that was associated with repeated inflammation was established for investigating the immunopathogenesis of CAC. This review discusses the role of T cell-mediated immune response, and DCs and involved cytokines in the immunopathogenesis of CAC in an animal model, which may also provide future therapeutic targets in CAC.

Mechanisms of Immune Signaling in Colitis-Associated Cancer

The inflammatory bowel diseases ulcerative colitis and Crohn’s disease are associated with an increased risk for the development of colorectal cancer. During recent years, several immune signaling pathways have been linked to colitis-associated cancer (CAC), largely owing to the availability of suitable preclinical models. Among these, chronic intestinal inflammation has been shown to support tumor initiation through oxidative stress–induced mutations. A proinflammatory microenvironment that develops, possibly as a result of defective intestinal barrier function and host–microbial interactions, enables tumor promotion. Several molecular pathways such as tumor necrosis factor/nuclear factor-κB or interleukin 6/signal transducer and activator of transcription 3 signaling have been identified as important contributors to CAC development and could be promising therapeutic targets for the prevention and treatment of CAC.

Tumor-Derived GM-CSF Promotes Inflammatory Colon Carcinogenesis via Stimulating Epithelial Release of VEGF

Chronic inflammation is a major driving force for the development of colitis-associated cancer (CAC). Elevated production of granulocyte macrophage colony-stimulating factor (GM-CSF) has been observed in mucosa of patients with inflammatory bowel disease. Its actions in the progression from colitis to cancer, however, remain poorly understood. Herein, we demonstrated that colonic epithelial cells (CEC) were a major cellular source of GM-CSF and its production was significantly augmented when CAC model was established by administration of azoxymethane and dextran sulfate sodium. Furthermore, we showed that GM-CSF was a driver for VEGF release by CEC in autocrine and/or paracrine manners through the extracellular signal-regulated kinase (ERK)-dependent pathway. Blocking GM-CSF activity in vivo significantly decreased epithelial release of VEGF, thereby abrogating CAC formation. In vitro treatment of transformed CEC with recombinant GM-CSF dramatically augmented its invasive potentials, largely in VEGF-dependent fashion. Furthermore, commensal microbiota-derived lipopolysaccharides were identified as a trigger for GM-CSF expression in CEC, as antibiotics treatment or Toll-like receptor 4 ablation considerably impaired its epithelial expression. Overall, these findings may have important implications for the understanding of mechanisms underlying CAC pathogenesis and the therapeutic potentials of regimens targeting GM-CSF or VEGF in clinic.

Potential of new anti-cancer agents targeting the nuclear translocation signaling of HB-EGF C-terminal fragments during the development of colitis-associated cancer

In inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn’s disease (CD), the duration and severity of inflammation are responsible for the development of colorectal cancer. Inflammatory cytokines such as interleukin (IL)-8 and tumor necrotic factor (TNF)-a, which are released by epithelial and immune cells, are involved in the pathogenesis of colitis-associated cancer. Current treatments for advanced colorectal cancers focus primarily on targeting epidermal growth factor receptor (EGFR) signaling. IL-8 (a G-protein coupled receptor (GPCR) agonist), which is involved in neutrophil recruitment and activation in persistent active colitis, also promotes cleavage of theproheparin-binding epidermal growth factor—like growth factor (proHB-EGF) through a disintegrin and metalloproteinase (ADAM), so that the resulting soluble HB-EGF activates EGFR. In parallel, the carboxy-terminal fragment of proHB-EGF (HB-EGF-CTF) translocates into the inner nuclear membrane, where HB-EGF-CTF binds the nuclear promyelocytic leukemia zinc finger (PLZF) protein, resulting in the nuclear export of the PLZF transcriptional repressor and thereby affecting cell proliferation. Screening for potent chemical inhibitors of the interactions between HB-EGF-CTF and PLZF identified telmisartan (and related compounds in corporating a biphenyl tetrazole moiety) as inhibitors of cell proliferation. Here we focus on the inhibitory effects of these compounds on cell proliferation, demonstrating the potential for targeting the nuclear translocation of HB-EGF-CTF in the treatment of colitis-associated cancer.

The role of IL-17 in modulation of antitumour immunity and progression of colitis-associated cancer

Colorectal carcinoma is one of the most frequent malignancies worldwide. There is a strong belief that it is initiated in the inflammatory bowel disease microenvironment. Pro-inflammatory cytokines produced by malignant cells as well as by tumor infiltrating leukocytes facilitate origination, growth and progression of cancer. An important role of T cells in antitumor immunity is well established. CD4+ Th lymphocytes can be classified into a few functional phenotypes: T helper 1 (Th1), T helper 2 (Th2), T helper 17 (Th17), according to the ability to secrete different cytokines. Th1 lymphocytes play important role in induction of cellular immunity, while Th2 lymphocytes suppress cellular immunity and enhance humoral immune response. Th17 lymphocytes are the key players in inducing inflammation by recruitment of neutrophils and macrophages. The polarization of T-mediated immune response has multiple effects on tumor progression. Although Th2-type cytokines can induce acute tumor rejection, Th1- type cytokines provide a greater antitumor effect and can promote durable anti-tumor CD8+T cell response. However, the role of IL-17 in pathogenesis of colitis-associated cancer (CAC) has not been fully understood. The aim of this paper is to clarify the role of IL-17 in modulation of antitumor immunity and progression of colorectal carcinoma.

Epidermal growth factor receptor inhibits colitis-associated cancer in mice

Inflammatory bowel disease (IBD) is a chronic illness caused by complex interactions between genetic and environmental factors that propagate inflammation and damage to the gastrointestinal epithelium. This state of chronic inflammation increases the risk for development of colitis-associated cancer in IBD patients. Thus, the development of targeted therapeutics that can disrupt the cycle of inflammation and epithelial injury is highly attractive. However, such biological therapies, including those targeting epidermal growth factor receptor pathways, pose a risk of increasing cancer rates. Using two mouse models of colitis-associated cancer, we found that epidermal growth factor receptor inactivation accelerated the incidence and progression of colorectal tumors. By modulating inflammation and epithelial regeneration, epidermal growth factor receptor optimized the response to chronic inflammation and limited subsequent tumorigenesis. These findings provide important insights into the pathogenesis of colitis-associated cancer and suggest that epidermal growth factor-based therapies for IBD may reduce long-term cancer risk.

173 TACE Inducer in Non-Pathogenic Intestinal Commensal Microbiota in Humans Promotes Colon Tumorigeneis via Accelerating of IL6 Trans-Signaling in Mucosal Dendritic Cells

Background /Aim Activation of the IL6/Stat3 via IL6 trans-signaling is important for the pathogenesis of colitis-associated cancer (CAC). TNFα converting enzyme (TACE) plays an essential role in triggering the cascade of IL6 trans-signaling by cleaving of IL6Rα on the cell membrane. TCRβ/p53 double knockout mice (DKO) spontaneously develop CAC in the presence of commensal bacteria in association with the increase of TACE+ F4/80+ lamina propria dendritic cells (LPDCs) in colonic mucosa. This study was aimed to elucidate the roles of commensal bacteria in the activation of TACE in F4/80+ LPDCs and the impacts of TACE-inducing bacteria on the colon-tumorigenesis of DKO. We also examined whether the activation of IL6 trans-signaling was actually involved in the colon-tumorigenesis caused by TACE-inducer in DKO. Method First, we examined TACE mRNA expression in F4/80+ LPDC cell line (iDEC5) stimulated by 45 strains of human commensal bacteria (C. coccoides, C. leptum, C.ramosum, Bacteroides, Prevotella, Bifidobacterium, Atopobium, Enterobacteriaceae, Lactobacillus, Fusobacterium, and Staphylococcus). Second, to investigate the role of TACEinducer on the colon-tumorigenesis of DKO, we compared the incidence of CAC in gnotobiotic (GB)-DKO colonized with TACE-inducer or TACE-uninducer. Finally, we examined the effects of soluble gp130Fc fusion protein (sgp130Fc), a competitive inhibitor of IL6 trans-signaling, on the colon-tumorigenesis in GB-DKO colonized with TACE-inducer. Results Human commensal bacteria were divided into three groups based on the activities to induce TACE mRNA expression in iDEC5; high TACE-inducer, intermediate TACEinducer and TACE-uninducer. GB-DKO colonized with TACE-inducer actually suffered from CAC, whereas TACE-uninducer did not cause CAC. Moreover, the colon-tumorigenesis in GB-DKO was associated with the massive infiltration of TACE+ F4/80+ LPDCs. Treatment of sgp130Fc significantly suppressed CAC in GB-DKO and reduced the infiltration of TACE+ F4/80+ LPDCs in colonic mucosa. Moreover, TACE activity and the expression level of phospho-STAT3 in the colonic mucosa of sgp130Fc group were significantly lower than those of control group.ConclusionCollectively, these results demonstrate that TACE-inducer derived from human commensal bacteria promotes colon-tumorigenesis via activation of IL6 trans-signaling in LPDCs.

174 DNA Hypermethylation of the Sda Carbohydrate Synthase Gene as a Possible Biomarker for the Prognosis of Ulcerative Colitis

Background /Aim Activation of the IL6/Stat3 via IL6 trans-signaling is important for the pathogenesis of colitis-associated cancer (CAC). TNFα converting enzyme (TACE) plays an essential role in triggering the cascade of IL6 trans-signaling by cleaving of IL6Rα on the cell membrane. TCRβ/p53 double knockout mice (DKO) spontaneously develop CAC in the presence of commensal bacteria in association with the increase of TACE+ F4/80+ lamina propria dendritic cells (LPDCs) in colonic mucosa. This study was aimed to elucidate the roles of commensal bacteria in the activation of TACE in F4/80+ LPDCs and the impacts of TACE-inducing bacteria on the colon-tumorigenesis of DKO. We also examined whether the activation of IL6 trans-signaling was actually involved in the colon-tumorigenesis caused by TACE-inducer in DKO. Method First, we examined TACE mRNA expression in F4/80+ LPDC cell line (iDEC5) stimulated by 45 strains of human commensal bacteria (C. coccoides, C. leptum, C.ramosum, Bacteroides, Prevotella, Bifidobacterium, Atopobium, Enterobacteriaceae, Lactobacillus, Fusobacterium, and Staphylococcus). Second, to investigate the role of TACEinducer on the colon-tumorigenesis of DKO, we compared the incidence of CAC in gnotobiotic (GB)-DKO colonized with TACE-inducer or TACE-uninducer. Finally, we examined the effects of soluble gp130Fc fusion protein (sgp130Fc), a competitive inhibitor of IL6 trans-signaling, on the colon-tumorigenesis in GB-DKO colonized with TACE-inducer. Results Human commensal bacteria were divided into three groups based on the activities to induce TACE mRNA expression in iDEC5; high TACE-inducer, intermediate TACEinducer and TACE-uninducer. GB-DKO colonized with TACE-inducer actually suffered from CAC, whereas TACE-uninducer did not cause CAC. Moreover, the colon-tumorigenesis in GB-DKO was associated with the massive infiltration of TACE+ F4/80+ LPDCs. Treatment of sgp130Fc significantly suppressed CAC in GB-DKO and reduced the infiltration of TACE+ F4/80+ LPDCs in colonic mucosa. Moreover, TACE activity and the expression level of phospho-STAT3 in the colonic mucosa of sgp130Fc group were significantly lower than those of control group.ConclusionCollectively, these results demonstrate that TACE-inducer derived from human commensal bacteria promotes colon-tumorigenesis via activation of IL6 trans-signaling in LPDCs.

Thrombin Supports Colitis and Colitis-Associated Cancer Pathogenesis

Abstract 2237Chronic inflammation has been recognized as a major factor in the development and progression of multiple cancers. A prime example of this is the strong association between colitis and colon cancer. However, the specific factors that regulate disadvantageous immune processes in the context of inflammation-associated cancers remain poorly defined. Growing evidence suggests that hemostatic system components, traditionally associated with the maintenance of vascular integrity and prevention of blood loss, also directly regulate inflammatory processes. Furthermore, thrombin and several thrombin targets (e.g., PARs, fibrinogen, factor XIII) have been shown to regulate tumor cell proliferation and apoptosis, support metastasis, and protect tumor cells from innate immune surveillance mechanisms in other experimental contexts. A logical extension of these findings is the hypothesis that thrombin, as a master regulator of both inflammatory processes and tumor cell biology, is a major determinant of the progression of inflammation-driven cancers such as colitis-associated colon cancer (CAC). To test this hypothesis, we induced CAC in mice carrying prothrombin levels 50% of normal (fII+/−) and WT mice in parallel using an established two step protocol consisting of azoxymethane (AOM) and dextran sodium sulfate (DSS) exposure. The modest diminution in prothrombin levels imposed by the fII+/− genotype resulted in a dramatic diminution in the number of colonic adenomas formed after AOM/DSS challenge relative to WT mice. In order to determine if the diminution in adenoma formation observed in fII+/− mice was coupled to thrombin function, wildtype mice challenged with AOM/DSS were treated with daily i.p. injections of hirudin, a direct thrombin inhibitor, or saline carrier. Similar to the finding in mice with a genetically-imposed diminution in circulating prothrombin, hirudin treatment significantly blunted adenoma formation. To determine if reduction of thrombin generation improved the inflammation preceding the development of colonic adenomas, we used a novel, highly-specific factor XI antisense oligonucleotide “gapmer” (ISIS Pharmaceuticals) to inhibit hepatic factor XI synthesis prior to DSS challenge. Gapmer-mediated diminution of fXI levels to ∼15% of normal resulted in a dramatic improvement in colitis related symptoms. Gapmer-treated mice had less intestinal bleeding and weight loss associated with DSS challenge relative to mice treated with a control oligonucleotide. Consistent with these gross observations, microscopic analyses of colonic tissue showed that fXI gapmer treatment significantly limited mucosal ulceration. Factor XI gapmer treatment also significantly diminished local levels of several inflammatory cytokines known to play a role in colon cancer progression (i.e., IL-6, IL-1β, IL-12). These results demonstrate that thrombin is a crucial driver of the pathogenesis of colitis-associated colon cancer and suggest that therapies directed at thrombin or thrombin generation could treat or prevent inflammation-driven colon cancer. As pathological inflammation has been estimated to account for as many as 1 in 5 cancer-related deaths, thrombin-directed therapies could have broad applicability to multiple malignancies. Disclosures:Mullins:Baxter: Consultancy. Monia:Isis Pharmaceuticals: Employment. MacLeod:Isis Pharmaceuticals: Employment. Revenko:Isis Pharmaceuticals: Employment. Palumbo:Novo Nordisk: Research Funding.

Animal models of colitis-associated carcinogenesis.

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that affect individuals throughout life. Although the etiology and pathogenesis of IBD are largely unknown, studies with animal models of colitis indicate that dysregulation of host/microbial interactions are requisite for the development of IBD. Patients with long-standing IBD have an increased risk for developing colitis-associated cancer (CAC), especially 10 years after the initial diagnosis of colitis, although the absolute number of CAC cases is relatively small. The cancer risk seems to be not directly related to disease activity, but is related to disease duration/extent, complication of primary sclerosing cholangitis, and family history of colon cancer. In particular, high levels and continuous production of inflammatory mediators, including cytokines and chemokines, by colonic epithelial cells (CECs) and immune cells in lamina propria may be strongly associated with the pathogenesis of CAC. In this article, we have summarized animal models of CAC and have reviewed the cellular and molecular mechanisms underlining the development of carcinogenic changes in CECs secondary to the chronic inflammatory conditions in the intestine. It may provide us some clues in developing a new class of therapeutic agents for the treatment of IBD and CAC in the near future.

Involvement of Cell Proliferation Induced by Dual Intracellular Signaling of HB-EGF in the Development of Colitis-Associated Cancer during Ulcerative Colitis

In ulcerative colitis (UC), the duration and severity of inflammation are responsible for the development of colorectal cancer. Reactive oxygen species (ROS), reactive nitric metabolites (RNMs) and interleukin (IL)-8, released by epithelial and immune cells, are involved in the pathogenesis of colitis-associated cancer. Nitric oxide and peroxynitrite activate epidermal growth factor receptor (EGFR), and therapeutic agents targeted towards EGFR are currently used to treat advanced colorectal cancer. IL-8 (a G-protein coupled receptor (GPCR) agonist), which is involved in neutrophil recruitment and activation in persistent active colitis, also promotes cleavage of the proheparin-binding epidermal growth factor-like growth factor (proHB-EGF) through a disintegrin and metalloproteinase (ADAM). The cleaved HB-EGF and C-terminal fragments (intracellular CTF) regulate proliferation via EGFR activation and nuclear export of promyelocytic leukemia zinc finger, transcription repressor, respectively. Here, we focus on the mechanisms by which RNM- and IL-8-induced EGF signaling regulate cell proliferation during the development of colitis-associated cancer.

Inflammation and Colon Cancer

The connection between inflammation and tumorigenesis is well-established and in the last decade has received a great deal of supporting evidence from genetic, pharmacological, and epidemiological data. Inflammatory bowel disease is an important risk factor for the development of colon cancer. Inflammation is also likely to be involved with other forms of sporadic as well as heritable colon cancer. The molecular mechanisms by which inflammation promotes cancer development are still being uncovered and could differ between colitis-associated and other forms of colorectal cancer. Recent work has elucidated the role of distinct immune cells, cytokines, and other immune mediators in virtually all steps of colon tumorigenesis, including initiation, promotion, progression, and metastasis. These mechanisms, as well as new approaches to prevention and therapy, are discussed in this review.

Abstract 2335: Role of heparanase in colitis associated cancer

Abstract Ulcerative colitis (UC) is a chronic inflammatory bowel disease that is closely associated with colon cancer. Here we report that heparanase enzyme acts as an important mediator of colitis-associated tumorigenesis. Heparanase is an only known mammalian enzyme that cleaves heparan sulfate, the major polysaccharide of the extracellular matrix, and plays multiple roles in inflammation and cancer progression. Applying histological specimens from UC patients and a mouse model of dextran sulfate sodium (DSS)-induced colitis, we found that heparanase is constantly overexpressed and activated during the course of the disease, both in the active and inactive phases of inflammation. Employing heparanase-overexpressing transgenic mice in the model of colitis-associated cancer, induced by carcinogen azoxymethane followed by repeated DSS administration, we demonstrated that heparanase overexpression markedly increased the incidence and severity of colitis-associated colonic tumors, enabling faster tumor take, angiogenic switch and enhanced tumor progression. Notably, DSS-induced colitis alone (without azoxymethane pretreatment) lead to formation of colonic tumors in heparanase-transgenic, but not wild type mice, positioning heparanase as important physiological determinant in inflammation-driven colon carcinoma, replacing the need for carcinogen. Investigating molecular mechanisms underlying heparanase induction in colitis, we found that macrophage-derived cytokines (i.e., TNFalfa) are responsible for continuous overexpression of heparanase by chronically-inflamed colonic epithelium. Moreover, our results suggest the occurrence of heparanase-driven vicious cycle that power colitis and associated tumorigenesis: heparanase activity in inflamed colon, acting synergistically with the local cytokine milieu, stimulates macrophage activation, and the activated macrophages secrete TNFalfa which stimulate further production of heparanase by colonic epithelium. In addition, activated macrophages secrete cathepsin L - a cysteine protease responsible for proteolytic activation of latent heparanase enzyme. Altogether, our results identify heparanase as a key factor in pathogenesis of colitis-associated cancer and attest macrophages as both heparanase regulators and cellular target for heparanase action. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2335.

Abstract C251: Heparanase mechanistically links chronic colitis and tumorigenesis

Abstract Ulcerative colitis (UC) is a chronic inflammatory bowel disease that is closely associated with colon cancer. Here we report that heparanase enzyme acts as an important mediator of colitis-associated tumorigenesis. Heparanase is an only known mammalian enzyme that cleaves heparan sulfate, the major polysaccharide of the extracellular matrix, and plays multiple roles in inflammation and cancer progression. Applying histological specimens from UC patients and a mouse model of dextran sulfate sodium (DSS)-induced colitis, we found that heparanase is constantly overexpressed and activated during the course of the disease, both in the active and inactive phases of inflammation. Employing heparanase-overexpressing transgenic mice in the model of colitis-associated cancer, induced by carcinogen azoxymethane followed by repeated DSS administration, we demonstrated that heparanase overexpression markedly increased the incidence and severity of colitis-associated colonic tumors, enabling faster tumor take, angiogenic switch and enhanced tumor progression. Notably, DSS-induced colitis alone (without azoxymethane pretreatment) lead to formation of colonic tumors in heparanase-transgenic, but not wild type mice, positioning heparanase as important physiological determinant in inflammation-driven colon carcinoma, replacing the need for carcinogen. Investigating molecular mechanisms underlying heparanase induction in colitis, we found that TNF-alpha is responsible for continuous overexpression of heparanase by chronically-inflamed colonic epithelium. Moreover, our results suggest the occurrence of heparanase-driven vicious cycle that powers colitis and associated tumorigenesis: heparanase activity in inflamed colon, acting synergistically with the local cytokine milieu, stimulates macrophage activation, and the activated macrophages secrete TNF-alpha which stimulate further production of heparanase by colonic epithelium. In addition, activated macrophages secrete cathepsin L - a cysteine protease responsible for proteolytic activation of latent heparanase enzyme. Altogether, our results identify heparanase as a key factor in pathogenesis of colitis-associated cancer and attest the inhibition of heparanase as a promising mean to disrupt the vicious cycle that fuels chronic colitis and the associated tumorigenesis. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C251.

Cytokines in Colitis-Associated Cancer: Potential Drug Targets?

In inflammatory bowel disease (IBD), such as UC and CD, the development of colorectal carcinoma can be initiated through chronic inflammation, depending on the duration and severity of the disease. Growing evidence supports a role for various cytokines, released by epithelial and immune cells, in the pathogenesis of colitis associated cancer (CAC). For instance, TNF-alpha has been recently shown to promote tumor development in experimental colitis. Due to its role in the pathogenesis of IBD, TNF-alpha blockade has become one of the cornerstones of IBD therapy. Thus, anti-TNF-alpha strategies could also provide effective anti-tumor therapies. TGF-beta has been shown to attenuate an anti-tumor immune-response through the induction of regulatory T cells in spontaneous and inflammation associated cancer. However, IL-6 signaling promotes tumor growth in experimental CAC, and this signaling is inhibited by TGF-beta. Members of the IL-12 family, such as IL-12, IL-23, and IL-27, have been implicated in pathogenesis of colitis and IL-23 seems to be involved in inflammation associated carcinogenesis. However, a role for those cytokines in CAC remains to be shown. Whereas the above-mentioned cytokines promote tumor growth, others provide an anti tumor effect. IL-10 deficient mice develop colitis and CAC a few weeks after birth. Besides its immunosuppressive properties, IL-10 also has anti angiogenic and both tumor promoting and -inhibiting properties, which could be responsible for these observations. Since most of the above mentioned cytokines are involved in both, inflammation and carcinogenesis, it is difficult to account their contribution to the individual steps during pathogenesis of CAC. However, as already shown in IBD, cytokines may also provide promising therapeutic targets in CAC.